which used to treat off-heap slots as on-heap ones and implement code target
visitation in derived visitor classes.

Bug: v8:8518
Change-Id: I477bf3a4a8a3de0c67bc15e2e20d8ecee6493da8
Reviewed-on: https://chromium-review.googlesource.com/c/1367745Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58121}